Okay, so I was thinking about breeding B/N pleco's but it seems as though that will never happen, so could I keep in my 30g tank some form of goldfish with maybe 5 WCMM? I want it to be a coldwater tank, can I keep MTS in a coldwater tank?_________________

A 30 gallon would be too small for a Bluegill, let alone 2 or 3 of them. However, your original plan of a Goldfish and a shoal of White Clouds is fine. With Goldfish, make sure you have a great filter as they are massive waste producers. On the type of Goldfish, I would go with some sort of Fancy. This variety is well suited for aquarium life as opposed to others._________________2500 gallon (9,450 L) Koi Pond
15 gallon (57 L) Low-light planted
6 gallon (23 L) Betta splendens

Yeah, I'd scratch the bluegill idea. Tank is too small for them after a a year or so of age. You don't have to steer clear from native completely though.
If you don't mind paying for them, I can give you some reputable contacts for purchasing natives. If you are want sunfish, you can go with dollar sunfish (aggressive) or orangespotted sunfish(docile) or bantam(docile) that max out around 4 inches. Or the smaller (but harder to feed) Bluespotted, banded, blackbanded sunnies.

If want to start natives, I'd say go with the minnows. you may be able t find some in a baitshop this spring.

Otherwise I say go with a big group of white clouds - they were one of my favorite fish when I kept them. And maybe a few loaches (weather/dojo) to keep it with an Asian theme. Java fern and the like.

I am only familiar with fishes of the eastern US, not that far west/north. I can't really help. But if you know what watershed you are in, you can look here and find it.
http://www.natureserve.org/getData/dataSets/watershedHucs/index.jsp
Click on your watershed and a list of species will come up. These lists are accurate, but only include the native fishes. They do not include introduced species (such as bluegill, redears, green sunfish, and baitfish like red shiners, golden shiners, or sticklebacks). You may be able to find these where they have been introduced. That is also why I recommended a baitshop, b/c they will have US native (although they may not be native to your area).
The only problem with that part of the country is you are (for the most part) limited to the Salmonids and the sculpins. While sculpin make very interesting aquarium specimens, they prefer cold, highly oxygenated water and will eat anything that will fit into that huge mouth of theirs. You may have a the olympic mudminnow or some sort of dace/shiners, but you will have to see.

If you do decide to go out and explore/catch your own. Brush up on ID skills or go out with someone who does, and make sure you have read your regulations and have the proper license, permit, collecting gear, etc.

Sounds good. I clicked on the methow river which is nearest to my house and found one fish that may be suited to aquarium life but am not sure, it is the Northern Pikeminnow, do you have any information on this fish?_________________

Longnose dace are good aquarium species but are very bad at jumping. They also are finicky about water parameters, so very clean, clear and cold water is good. They are very bad about leaping out of the tank. so a tight lid and a powerhead is a must. The powerhead keeps them 'focused' and they will not try to leap near your powerfilter to 'try and find more water upstream'.

So do some research on the legality of keeping / catching fish in your area then we can discuss collecting techniques. These guys are in swift water, and the best way to get them is with a minimum of two people. I'll go into deeper detail once you make a decision and find out about the laws and legality for Washington.

Okay, so assuming I can catch the dance due to laws and I find where they are at in the river, what would be needed for them to thrive in my tank and how do I keep the temp cool during the summer months?_________________